Quantitative electroencephalography in mild cognitive impairment: longitudinal changes and possible prediction of Alzheimer's disease

The present study evaluated the clinical course of patients with mild cogni tive impairment (MCI), the pattern of electroencephalography (EEG) changes following cognitive deterioration, as well as the potential of neurophysiol ogical measures in predicting dementia. Twenty-seven subjects with MCI were followed for a mean follow up period of 21 months. Fourteen subjects (52%) progressed (P MCI) to clinically manifest Alzheimer's disease (AD), and 13 (48%) remained stable (S MCI). The two MCI subgroups did not differ in bas eline EEG measures between each other and the healthy controls (n = 16), bu t had significantly lower theta relative power at left temporal, temporo-oc cipital, centro-parietal, and right temporo-occipital derivation when compa red to the reference AD group (n = 15). The P MCI baseline alpha band tempo ro-parietal coherence, alpha relative power values at left temporal and tem poro-occipital derivations, theta relative power values at frontal derivati ons, and the mean frequency at centro-parietal and temporo-occipital deriva tions overlapped with those for AD and control groups. After the follow-up, the P MCI patients had significantly higher theta relative power and lower beta relative power and mean frequency at the temporal and temporo-occipit al derivations. A logistic regression model of baseline EEG values adjusted for baseline Mini-Mental Test Examination showed that the important predic tors were alpha and theta relative power and mean frequency from left tempo ro-occipital derivation (T5-O1), which classified 85% of MCI subjects corre ctly. (C) 2000 Elsevier Science Inc. All rights reserved.